Children who want to be vegetarians need to “fill in the blanks” of their low-protein diets by eating alternatives to red meat, fish and poultry, experts say.

Good examples are soybeans, fortified soy milk and nuts. Those are important sources of the protein, iron, zinc, calcium and vitamin D that most kids get from meat.

Nutritional yeast — which has a cheesy flavour — has the much-needed vitamin B12. And flaxseed is good for linolenic acid.

Vegetarian children who eat eggs and dairy products will most likely get all the nutrition they need. But those who become vegan — abstaining from dairy — need to be more diligent, said Dr. David Ludwig of Children's Hospital Boston, a specialist in pediatric nutrition.

Children can start on a vegetarian diet from birth, said Sarah Krieger, a spokeswoman for the American Dietetic Association who is a registered dietitian at All Children's Hospital in St. Petersburg, Fla.

Breast milk or an iron-fortified formula are necessary in the first six months, she said, adding that soy-based formula is an option.